The present invention relates to semiconductor devices, and more specifically, a technique that can be applied to a semiconductor device including a solid-state image sensor.
Solid-state image sensors using a complementary metal oxide semiconductor (CMOS) have been developed as one of solid-state image sensors. The CMOS image sensor includes a plurality of pixels having a photodiode and a transfer transistor.
For example, Patent Document 1 (Japanese Unexamined Patent Publication 2007-165450) discloses a solid-state image sensor with pixels including a photoelectric conversion part for generating and storing charges according to an incident light, and a charge detection region to which the charges stored in the photoelectric conversion part are transferred. In the technique disclosed, a charge storage region of the photoelectric conversion part is formed of a first semiconductor layer of a first conductive type. An isolation region for electrically isolating one pixel from the other adjacent thereto is formed of a semiconductor layer of a second conductive type. A high-concentration second semiconductor layer of the first conductive type located in the isolation region forms a gettering layer.
Patent Document 2 (Japanese Unexamined Patent Publication 2007-88406) discloses a CMOS image sensor that can reduce leakage current by gettering metal ion contamination by implanting p-type impurity ions in a high concentration, into a dummy moat region.
Patent Document 3 (Japanese Unexamined Patent Publication 2002-353434) discloses a technique which involves forming an embedded getter sink layer by introducing carbon (c) into a semiconductor substrate, forming a crystal growth layer by growing Si crystals over the surface of a semiconductor substrate, and forming a solid-state image sensor in the crystal growth layer.